主动配电网短路电流水平在线估计及全过程管理

The project conceptually proposes to dynamically monitor the potential short-circuit current contributions of distributed generation (DG) and assess the management effectiveness of different networks and sources to the short-circuit level, and use this to maximize the generation contributed from embedded DG. On the analysis methods, the research will develop the estimation algorithms for the impulse factor of peak short-circuit current and the correction factor of short-circuit breaking current by investigating the DC component change law of short-circuit current form DG with different grid interfaces. Afterward, according to the constructed short-circuit calculation models of DG, the equivalent circuits in the transient and steady-state phases can be derived and inserted into the fault component network of active distribution grid. Then taking the node voltage and DG output power in the normal operation network, the transient features of DG during grid disturbances as the measured variables, regarding the parameters of DG equivalent circuit and the branch short-circuit currents in the fault component network as the state variables, the joint estimation model of short-circuit currents and DG parameters can be established to online evaluate the system short-circuit level. Furthermore, a method to judge the predictive control feasibility of short-circuit level of active distribution network will be proposed, comprehensively considering the short-circuit regulation measures of DG output power, network structure, controllable load and fault current limiting equipment. Subsequently the compromise control strategy of short-circuit level in the unfeasibility stage can be designed using the soft constraint adjustment, and then the critical condition for upgrading and rebuilding the distribution equipments can be determined. As an intended outcome of this research, the online monitoring, evaluation and control can be implemented for the whole-process dynamic management of short-circuit current level in active distribution networks.

本项目在概念上提出实时追踪分布式发电（DG）对潜在短路电流的贡献、评估不同网络和电源的短路水平管理效果，为主动配电网最大限度地接入DG创造条件。在分析方法上，研究不同特性DG短路电流及其直流分量的变化规律，探寻冲击系数及开断电流校正系数的估算方法；由DG短路计算解析模型得到其在暂态和稳态阶段的等效电路，加入配电网故障分量网络中，用正常网络电压、DG出力和电网扰动时DG暂态特征量作为测量量，以DG等效电路参数、故障网络支路短路电流为状态量，建立DG参数和配电网短路电流联合估计模型，在线评估系统短路水平。在应用途径上，综合考虑DG出力、网络结构、可控负荷和限流设备等措施，探讨短路水平预测控制可行性的判定方法，利用约束软化处理，设计不可行阶段的短路水平折衷控制策略，进而确定配电设备升级改造的临界条件。本项目最终期望达到对主动配电网预期短路电流水平在线监测、评估和控制的全过程进行动态智能管理。

主动配电网短路水平管理是提高DG接纳能力和保障电网安全运行的重要措施。本项目建立了计及不脱网可控性的DG短路计算模型，结合短路电流迭代计算方法、工程实用计算方法和直流分量计算和一致性测试，提出了配电设备短路校验的校正方法。分析了不同特性DG对电压暂降扰动的响应特性，建立了主动配电网短路电流和DG等效电路参数的联合估计模型，提出了系统短路水平变化的在线评估方法。研究了主动配电网限流设备等效阻抗和短路电流调节措施，设计了主动配电网短路水平的多目标约束预测控制策略，提出了短路电流调节措施的全过程动态管理方法。研究了支撑短路电流水平动态管理的信息和通讯技术、就地智能测控设备，按照决策方案确定控制指令触发时序和通讯流程，设计了主动配电网短路电流水平监测及决策支持系统。本项目的顺利实施为智能配电网的短路水平主动控制和管理功能提供理论和技术支撑，为我国建设坚强智能电网以及保障电网稳定运行、用户可靠供电提供重要的工程应用价值。